The pressure of standing and walking in shoes creates friction between a wearer's feet and shoes. Moisture accumulation inside shoes increases shoe-skin friction and the likelihood of blistering. Thus, discomfort and even skin breakdown may be caused by a natural build-up of moisture and the interaction of moisture with movement of a person's feet inside shoes.
In general, foot coverings designed to decrease moisture and associated friction between a wearer's foot and a shoe have been constructed with various combinations and arrangements of both hydrophobic (water-repelling) and hydrophilic (water-absorbing) yarns. An objective of such configurations of hydrophobic and hydrophilic yarns is to provide fabrics with a relatively low moisture regain, or ability to absorb moisture, particularly on a sock surface adjacent to skin. Moisture regain is defined as the moisture present in textile material expressed as a percentage of the moisture-free weight of the material. (Phyllis G. Tortora & Robert S. Merkel, Fairchild's Dictionary of Textiles, 7th Edition, page 465.) A low moisture regain indicates that a fabric, and yarn from which it is made, has a relatively low moisture content. A fabric with a relatively low moisture regain, and thus less retained moisture content, would provide more comfort to a wearer than a fabric with a relatively high moisture regain.
In some arrangements, hydrophilic yarn is placed in high-moisture areas of a foot to absorb moisture. For example, U. S. Pat. No. 4,898,007 to Dahlgren disclose placing hydrophilic yarn, such as cotton or wool, in the toe, heel, and ball areas of al sock and hydrophobic yarn, such as a nylon/acrylic blend, in the sole and instep areas. Such placement is based on the premise that moisture is absorbed by hydrophilic yarn in the toe, heel, and ball areas and is then transferred by wicking action into the hydrophobic yarn away from pressure points and into the middle portion of the foot. In other arrangements, rather than limiting placement of hydrophilic yarn to particular regions of a foot, hydrophilic yarn is placed on the inside of a fabric for direct contact with the skin of most, or all, of a foot. These constructions, however, have the disadvantage of placing high moisture regain, hydrophilic yarns in constant contact with the skin of a foot. Accordingly, sock constructions in which hydrophilic yarn is in contact with skin are more likely to keep the skin moist and create greater susceptibility to friction and blisters.
In contrast, other approaches to moisture management include placement of moisture-repelling hydrophobic yarn in particular regions of a sock, such as areas in contact with high moisture areas of a foot. As an example, U.S. Pat. No. 5,095,548 to Chesebro discloses placing hydrophobic yarn, such as an olefin yarn, in the sole portion of a sock while hydrophilic yarn, such as a blend of cotton and acrylic, is placed in the instep area above the sole. In this arrangement, moisture generated by the foot of the wearer is wicked by the hydrophobic yarn from one part of the foot (the sole) and transported to another part of the foot (the hydrophilic instep) to be evaporated therefrom.
Moisture management socks have also been knit with hydrophobic and hydrophilic yarns in combinations with body yarn. For example, in the Chesebro patent mentioned above, a body yarn, such as nylon, is knit in successive courses throughout the sock. Hydrophobic yarn is knit in plated relationship with the body yarn in partial courses extending throughout the sole, and hydrophilic yarn is knit in plated relationship with the body yarn in partial courses extending throughout the instep. While use of body yarn allows non-contiguous placement of hydrophobic and hydrophilic yarns, body yarn disadvantageously increases the bulk of resulting socks.
Combinations of hydrophobic yarn and hydrophilic yarn have also been used in socks having multiple layers. U.S. Pat. No. 4,615,188 to Hursh et al. discloses such a multi-layered sock, the first ply inner layer having a surface adapted to contact the skin and formed principally of low moisture regain hydrophobic yarns, such as polypropylene and polypropylene/wool combinations. In this design the hydrophobic yarns have undesirable high frictional characteristics in order to grip the skin so that inter-layer surfaces may slide against each other. Multi-ply socks are disadvantageous in that they are bulky and tend to bunch up, thereby causing abrasion, blisters, and discomfort.
Socks designed to enhance the movement of moisture away from a wearer's foot have also been used in conjunction with a particular shoe construction, for example, shoes designed to vent moisture absorbed by the sock away from a foot. Usefulness of these types of moisture management socks is limited due to the need to use such socks with a specially designed shoe.
In yet other sock constructions, moisture management is provided by plating hydrophobic yarn on the inside of a sock for contact with a wearer's foot, while hydrophilic yarn is plated on the outside of the sock. In such an arrangement, moisture generated by the foot of a wearer is wicked and transported by the hydrophobic yarn outwardly away from the foot, where it is absorbed by the hydrophilic yarn on the outside of the sock, and held away from the foot and/or evaporated from the sock. An example of this type of construction is given in U.S. Pat. No. 3,250,095 to Bird, which discloses hydrophobic yarn including synthetic yarns such as acrylic, and hydrophilic yarn as cotton, rayon, wool, silk, or combinations thereof.
Previous approaches to managing moisture via sock construction have had varied success. Thus, there is a need to provide an improved sock construction that can effectively manage moisture build-up on the foot of a wearer and decrease friction and the likelihood of blisters.
It has been found that mohair wool, a naturally moisture-wicking fiber, effectively manages moisture in a sock and decreases the friction-promoting effects of moisture on a foot. In addition, mohair wool is a slick fiber that allows a foot to move inside a sock with less friction and protects against blisters by cushioning the foot. Prior sock constructions designed to provide moisture management have not utilized mohair wool as a hydrophobic yarn placed on the inside surface of a sock for contact with a wearer's skin blended with a hydrophilic yarn on the outer sock surface. As such, the advantages of a mohair wool/hydrophilic yarn blend have not been used to improve moisture management in a sock that overcome the disadvantages of other sock constructions.
Thus, there is a need for a sock having improved moisture management utilizing low moisture regain mohair wool yarn on the inside surface of a sock in a single layer that provides a high quality hand and enhanced comfort. In addition, there is a need for providing an improved moisture management sock construction using mohair wool that can be easily and economically manufactured and used. It is to these perceived needs that the present invention is directed.